Soldering electronic components on a printed circuit board has previously been performed using an automatic soldering apparatus. On the automatic soldering apparatus, it is configured so that a fluxer, a preheater, a jet solder bath, a cooling apparatus and the like are arranged at their predetermined positions. In this automatic soldering apparatus, when soldering the electronic components on the printed circuit board, the fluxer applies flux over the entire back surface of the printed circuit board, the preheater preliminarily heats the printed circuit board, an entire jet solder bath solders the electronic components on the printed circuit board, and the cooling apparatus cools the molten solder, thereby finishing the soldering steps.
When soldering the printed circuit board on the back surface of which surface-mount components, connectors and the like are mounted by the automatic soldering apparatus having the above-mentioned entire jet solder bath, any issues occur in the surface-mount components, connectors and the like. For example, in the entire jet solder bath, the flux is applied to the entire back surface thereof, the entire back surface is preliminarily heated, and molten solder is then contacted with the entire back surface thereof.
Because of this, the surface-mount components mounted on the back surface thereof contact the molten solder which has become a high temperature so that failure in function, thermal damage brings about in them, and the molten solder enters into jack insert holes of the connectors mounted on the back surface thereof so that a bad contact occurs, which runs into a situation that they cannot be used at all as the connectors.
Accordingly, accompanying a miniaturization of electronic components, a partial-jet-soldering device has often been adapted which contacts the molten solder to only desired positions in the printed circuit board and can perform the soldering without exerting any thermal influence upon undesired positions therein.
In relation to such a partial-jet-soldering device, in a patent document 1, a partial-jet-soldering method for a printed circuit board and a partial-jet-soldering device therefor are disclosed. In the partial-jet-soldering device, a jet pump and many nozzles each having a tubular shape are arranged in a partial jet solder bath and at the inside thereof, the solder is kept its melted condition by a heater. Set-up positions of the nozzles are set so that they align a soldering group in the printed circuit board. In the partial jet solder bath using many nozzles, based on Pascal's principle, pressure applied to each nozzle from a solder sending path becomes identical at each nozzle position, which is a situation where pressure by which the molten solder is sent by the jet pump and pressure applied to all the nozzles are in balance with each other.
According to this partial-jet-soldering method, it is disclosed to mount the printed circuit board on the nozzles while many soldering groups in the printed circuit and many nozzles set in the partial jet solder bath board are aligned with each other, and then, to raise the molten solder in the nozzles inside the nozzles to contact it with the soldering groups in the printed circuit mounted on the nozzles and to circulate the molten solder in the nozzles. If the device is configured so as to do so, it is possible to obtain any soldered positions having good reliability wherein, when soldering the printed circuit board, any undesired solder is not only adhered to the surface-mount components or the connectors, which are mounted on the back surface thereof, but the solder also completely enters into through-holes.
Further, in a patent document 2, a flow soldering apparatus is disclosed. According to this flow soldering apparatus, when spouting molten solder from jet nozzles to locally solder electronic components on printed circuit board, a dummy jet nozzle and means for detecting a surface of liquid are provided therein. The dummy jet nozzle is positioned at a position which is near the jet nozzles and off the printed circuit board carried to a position to be soldered and positioned thereto. The means for detecting a surface of liquid is configured so that it detects a height of the molten solder spouted from the dummy jet nozzle. If the flow soldering apparatus is configured so as to do so, it is possible for the means for detecting a surface of liquid to detect the height of the molten solder spouted from the dummy jet nozzle, thereby enabling the height of the molten solder thus spouted to be grasped even during performing the soldering and allowing for dealing with any variations in the height of the molten solder thus spouted on a real-time basis.
Additionally, in relation to a jet pump that sends molten solder, in a patent document 3, a solder bath pump is disclosed. According to this solder bath pump, a screw is positioned in an interior space through which a casing is passed so that it can be rotated. The screw is configured so that plural spiral blades project outwardly from a rotation shaft thereof with them being positioned at regular intervals on a circumferential direction thereof and all the spiral blades encircle around the rotation shaft on the basis of a direction of an axis of the shaft. If the pump is configured so as to do so, it is possible to send the solder efficiently, as compared with the conventional pump, because the solder can be sent out evenly from an entire bottom surface of the screw excluding an area just blow the rotation shaft.
Prior Art Documents
Patent Documents
Patent Document 1: Japanese Patent Application Publication No. 2002-368404;
Patent Document 2: Japanese Patent Application Publication No. 2000-200966; and
Patent Document 3: Japanese Patent Application Publication No. 2005-028446.